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virtio-net: calculating proper msix vectors on init 

Currently, the default msix vectors for virtio-net-pci is 3 which is
obvious not suitable for multiqueue guest, so we depends on the user
or management tools to pass a correct vectors parameter. In fact, we
can simplifying this by calculating the number of vectors on realize.

Consider we have N queues, the number of vectors needed is 2*N + 2
(#queue pairs + plus one config interrupt and control vq). We didn't
check whether or not host support control vq because it was added
unconditionally by qemu to avoid breaking legacy guests such as Minix.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
This commit is contained in:
Jason Wang 2021-03-08 12:49:19 +08:00
parent 6157b0e197
commit 51a81a2118
2 changed files with 10 additions and 1 deletions
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1
hw/core/machine.c
View File

@ -39,6 +39,7 @@
GlobalProperty hw_compat_5_2[] = {
{ "ICH9-LPC", "smm-compat", "on"},
{ "PIIX4_PM", "smm-compat", "on"},
{ "virtio-net-pci", "vectors", "3"},
};
const size_t hw_compat_5_2_len = G_N_ELEMENTS(hw_compat_5_2);

10
hw/virtio/virtio-net-pci.c
View File

@ -41,7 +41,8 @@ struct VirtIONetPCI {
static Property virtio_net_properties[] = {
DEFINE_PROP_BIT("ioeventfd", VirtIOPCIProxy, flags,
VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, true),
DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 3),
DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors,
DEV_NVECTORS_UNSPECIFIED),
DEFINE_PROP_END_OF_LIST(),
};
@ -50,6 +51,13 @@ static void virtio_net_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
DeviceState *qdev = DEVICE(vpci_dev);
VirtIONetPCI *dev = VIRTIO_NET_PCI(vpci_dev);
DeviceState *vdev = DEVICE(&dev->vdev);
VirtIONet *net = VIRTIO_NET(vdev);
if (vpci_dev->nvectors == DEV_NVECTORS_UNSPECIFIED) {
vpci_dev->nvectors = 2 * MAX(net->nic_conf.peers.queues, 1)
+ 1 /* Config interrupt */
+ 1 /* Control vq */;
}
virtio_net_set_netclient_name(&dev->vdev, qdev->id,
object_get_typename(OBJECT(qdev)));